Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

The number one question in sleep research is “Why do we sleep?”—followed by the question, “How much sleep do we need?” After literally hundreds of studies, we still don’t know the best answer to either question. A few years ago, I featured a large 100,000 person study suggesting that “Both short and long sleep duration were associated with increased mortality,” with people getting around 7 hours of sleep living longest.

Since then, a meta-analysis of all such studies including more than a million people was published, and they found the same thing. We still don’t know, though, if “sleep duration is a cause or simply a marker of ill-health.” Maybe, sleeping too little or too long does make you unhealthy. Or, maybe we see the associated lifespan shortening because being unhealthy causes you to sleep shorter or longer.

Similar work has now been published on cognitive function. After controlling for a long list of factors, men and women in their 50s and 60s getting seven or eight hours appeared to have the best short-term memory, compared to those that got much more, or much less. Same thing was just demonstrated with immune function: “Both reduced and prolonged habitual sleep durations [were] associated with [an] increased risk of pneumonia.”

It’s easy to prevent over-sleeping; set an alarm. But, what if your problem is not getting enough? What if you’re the one in three adults that suffers symptoms of insomnia? Sure, there are drugs, like Valium, you can take for insomnia in the short-term. But, they have a number of adverse side effects. And non-pharmacological approaches, such as cognitive behavioral therapy, are “often difficult,…time-consuming,” and don’t always work. Wouldn’t it be great to have “natural treatments that can improve both sleep onset and help patients improve the quality of sleep while improving next-day symptoms over the long term?”

The “Effect of kiwifruit consumption on sleep quality in adults with sleep problems.” Two kiwifruit an hour before bed, every night, for four weeks. Why study kiwifruits? Well, people with sleep disorders tend to have high “levels of oxidative stress,” so, antioxidant-rich foods might help. But, all fruits and vegetables have antioxidants. Ah, but kiwifruits contain twice the serotonin of tomatoes. But, it really shouldn’t cross the blood/brain barrier. Kiwifruit has folate, and a deficiency might cause insomnia, but, there’s lots more folate in some other plant foods.

The reason they studied kiwifruits is because they got grant money from a kiwifruit company. And, I’m glad they did, because they found some really remarkable results: significantly improved sleep onset, duration, and efficiency using both subjective and objective measurements. Went from sleeping six hours a night to seven, just eating a few kiwifruit.

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

The number one question in sleep research is “Why do we sleep?”—followed by the question, “How much sleep do we need?” After literally hundreds of studies, we still don’t know the best answer to either question. A few years ago, I featured a large 100,000 person study suggesting that “Both short and long sleep duration were associated with increased mortality,” with people getting around 7 hours of sleep living longest.

Since then, a meta-analysis of all such studies including more than a million people was published, and they found the same thing. We still don’t know, though, if “sleep duration is a cause or simply a marker of ill-health.” Maybe, sleeping too little or too long does make you unhealthy. Or, maybe we see the associated lifespan shortening because being unhealthy causes you to sleep shorter or longer.

Similar work has now been published on cognitive function. After controlling for a long list of factors, men and women in their 50s and 60s getting seven or eight hours appeared to have the best short-term memory, compared to those that got much more, or much less. Same thing was just demonstrated with immune function: “Both reduced and prolonged habitual sleep durations [were] associated with [an] increased risk of pneumonia.”

It’s easy to prevent over-sleeping; set an alarm. But, what if your problem is not getting enough? What if you’re the one in three adults that suffers symptoms of insomnia? Sure, there are drugs, like Valium, you can take for insomnia in the short-term. But, they have a number of adverse side effects. And non-pharmacological approaches, such as cognitive behavioral therapy, are “often difficult,…time-consuming,” and don’t always work. Wouldn’t it be great to have “natural treatments that can improve both sleep onset and help patients improve the quality of sleep while improving next-day symptoms over the long term?”

The “Effect of kiwifruit consumption on sleep quality in adults with sleep problems.” Two kiwifruit an hour before bed, every night, for four weeks. Why study kiwifruits? Well, people with sleep disorders tend to have high “levels of oxidative stress,” so, antioxidant-rich foods might help. But, all fruits and vegetables have antioxidants. Ah, but kiwifruits contain twice the serotonin of tomatoes. But, it really shouldn’t cross the blood/brain barrier. Kiwifruit has folate, and a deficiency might cause insomnia, but, there’s lots more folate in some other plant foods.

The reason they studied kiwifruits is because they got grant money from a kiwifruit company. And, I’m glad they did, because they found some really remarkable results: significantly improved sleep onset, duration, and efficiency using both subjective and objective measurements. Went from sleeping six hours a night to seven, just eating a few kiwifruit.

40 responses to “Kiwifruit for Insomnia”

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If they received “grant money from a kiwifruit company”, then why is their study any less biased than those studies you previously referred to that were funded by the salt or dairy or meat companies. Isn’t the whole purpose of science to reach objective explanations by eliminating biases? If so, shouldn’t we disregard all studies that are funded by corporations?

Just like we should take studies funded by the Salt Institute with a grain of salt, we should take these findings with a grain of kiwi :)

The difference between this and the other examples you cite is what’s the worst that can happen? Even if this data was totally fraudulent, the worst case scenario if someone follows this advice is that they eat a really healthy fruit and only get all its other benefits (even if it doesn’t actually help with sleep). That’s the wonderful thing about plant-based research!

And industry influence is rarely about outright fraud but about study design. One just has to be mindful about study sponsors to make sure the study wasn’t constructed in a way to bias the results.

re: “One just has to be mindful about study sponsors to make sure the study
wasn’t constructed in a way to bias the results. That is something for
which I am indeed constantly on the lookout.”

That’s what the average lay person (and according to Dr. Campbell, even the average scientist and medical professional) can’t do for themselves / must rely on a responsible expert for. That you care about this aspect of studies is one of the reasons I love your work.

Thanks for taking the time to answer BPCveg’s question as I think it was a good one. And you had a good answer too.

In reference to “industry influence is rarely about outright fraud. . .” I don’t know if you (or anyone reading this) has ever seen this documentary on the business of cancer but it will open anyone’s eyes to the corruption of the FDA, NCI (National Cancer Institute), ACS (American Cancer Society) and AMA (American Medical Association) and expose the outright fraud involved in Cancer treatment and the bias to ensure expensive, pharmaceutically based therapy and procedures.
Backed up from numerous hard statistics, peer reviewed articles, research and verifiable references.

Warning not a feel-good movie and will utterly disappoint one about the absolute corruption involved in the treatment (or lack thereof) of cancer.

Thanks for your reply, though I have to disagree with you.
You yourself have provided evidence that certain plant products (e.g. coconuts and avocados) are of dubious health value – but you had to cut through a lot of conflicting studies to reach those conclusions. So how come you are so accepting of corporate sponsored kiwi research? Is it any more obvious that a kiwi is beneficial than a coconut? Same question applies for any animal product!

I hope you were joking when you said that “industry influence is rarely about outright fraud but about nuanced study design”. Else it may be time to re-read ‘How to Lie with Statistics’ by Darrel Huff.

Corporations have no other interest than profit. They will bend-over-backward to skew research in their own favour.

I second the motion made by SFV below, which suggests that some kind of validity rating be provided to give your audience a sense of the credibility of any study that you report.

Meta analyses of studies funded by interest groups found that overwhelmingly, studies that are funded by a particular industry or producer of a particular product end up with findings in favor of that product. (I don’t have exact citations, but the rate was mentioned in “Proteinaholic” by Dr. Garth Davis, and was really suspiciously high, like 10:1 or something.) I don’t think it is sufficient to say that at worst, someone ends up eating more fruit; favorable findings can end up driving up the price of a particular fruit because of erroneous increases in demand based on bad findings, and that wastes people’s money if the effect they wanted isn’t real. Also, you said

“And industry influence is rarely about outright fraud but about study design. One just has to be mindful about study sponsors to make sure the study wasn’t constructed in a way to bias the results.”

Bias, even unconscious bias, on the part of the researchers could influence their findings. If the sample size is small (10’s of subjects rather than 100’s or 1000’s) for short periods of time, the study group could simply split their research subject pool of 200 into 10 sets of 20 subjects, and publish only the cohort with the best outcomes, and nobody would be the wiser. That top performing cohort would be far to one wing of the bell curve, and would simply not be representative of what the food actually does.

I think any study that seems too good to be true needs to be tested with great rigor. This includes the Brazil nut study on lowering cholesterol, the saffron studies, this study, etc. I’m not disputing the notion that kiwis are safer than drugs and that the relative risk of trying a less rigorous study done on plants is less, but to maintain your work as rigorously evidence based, you can’t let it appear as if you’re permitting yourself to slip into using double standards. You know critics of plant-based lifestyles will jump on any weakness to throw shade, and it does nobody any service to give critics an opportunity to dismiss your work.

Interesting, but I’m wondering if it’s just the combination of sugar and fiber in the kiwifruit that are doing the trick. Low blood sugar levels can raise your cortisol levels and keep you up at night, one of the reasons a little milk before bed has been recommended for years. Would a glass of soymilk do the same thing? Maybe the Silk people should fund a study.

Did that study have a control group or a placebo group? I can’t tell from the abstract, but it looked like it didn’t. Did the subjects know they were in a study designed to see if sleep could be improved eating kiwi?

I’d like to see the results of a study which subjects think is looking at whether kiwi impairs sleep. Probably they’d be up all night.

Did anyone else look at that time-lapse video of the baby and notice how underweight, colicky and covered with eczema he was for the first few months? I wonder if he had an undiagnosed dairy allergy. Poor thing. He did not look like a happy baby for quite a long time.

Hi Dr. Greger. I think it would be a big improvement if the videos could briefly indicate the limitations of the studies that are mentioned. There is basically no meaningful conclusion from a study with 24 subjects and no control group. Few people, if any, will be able to act on every study that you mention, so distinguishing well-designed studies and highly substantiated results and recommendations from methodologically weak studies and tentative conclusions would help viewers to focus on the most critical actions they can take to enhance their health. I know that’s what you are aiming for in your longer video summaries. I also understand that time is very limited on the daily video clips. Maybe you could have a 1-to-5 type validity rating for the studies that you cite. Viewers without a research background or a strong grounding in nutrition issues might come away thinking the the China Study and the kiwi study are equally valid. That would be a shame. I don’t want to end this comment without expressing my daily gratitude for the work that you are doing for the benefit of us all.

Would you please look into and report on perilla seeds?
It seems they are now being hailed as the next big “superfood” with the “selling factor” being their Omega 3 to Omega 6 ratio (allegedly 6:1).
Is there any truth to the claims or is this more hype?

I heard this somewhere a while ago, and we started offering our two year old daughter kiwi as dessert after dinner – and she has slept much, much better since then! Could be a coincidence though, because I agree with some of the writer above, this study is pretty dodgy (no control group, could all be placebo effect), but because my daughter loves Kiwi anyway, we switched it from lunch to dinner. We experimented a bit (no kiwi on day x, kiwi on day y) and she does sleep better after a kiwi. And so do we. Could still be due to something else, of course – but I do recommend other parents to try this if their children (age appropriate of course, not infants) like kiwi and don’t sleep so well.

Kiwis are kind of expensive, two for$1. I’m going to try banana peel tea before bed. I’ll eat the banana while boiling the peel for 10 minutes then drink the water the peel was boiled in. Anybody tried this? Most of the “recipes” for the tea have you boil the banana with the peel on, but I’m not to keen on warm soggy banana.

I have recently started eating according to Dr Michael Greger’s guidelines in HOW NOT TO DIE. I feel great in so many ways – digestion better, joints and muscles no longer tight and achey, etc. However, my SLEEP has gone out the window. I am waking hourly, often needing to go to the loo (to urinate), unable to totally settle into deep restorative sleep. In the past I have had irritable bladder from eating too much fruit so I am trying to focus on more veg rather than fruit in my wholefood plant based eating, in case this is the problem. The doctors have never found anything wrong as such. Poor sleep with frequent urination has been going on for a month and I am exhausted. Is there anyone who can offer me some support so I can get myself on track? I am unsure whether to try kiwis given the possible fruit/excess weeing link I have noticed in the past. But I am desperate to sleep!

Glad to hear you’re doing well generally following Dr. Greger’s guidelines, although I can appreciate your sleep problems. Because so many things affect sleep, certainly a review of those might be in order, recognizing that your assumption that increased fruit consumption may be contributing if fruits cause night time urination. If fruit shows a definite pattern of causing need to urinate at night, of course eating your fruit during the day makes sense, but you don’t want to give fruit up.. Why not try to rule out other causes and do a test with kiwis as well? Fortunately, adding a few kiwis won’t cause harm, other than possible continued sleepless night or two.
You’ve indicated you’ve consulted with doctors in the past for sleep problems. Were you given any advice about promoting sleep then? If your sleep problems don’t resolve after practicing all suggestions you’ve been given (and/or ones reviewed in the articles below) perhaps visiting a sleep specialist might be appropriate. Best of health and better sleep to you,http://ga.berkeley.edu/wp-content/uploads/2015/04/harvey_sleep_tips.pdfhttps://www.sleepassociation.org/patients-general-public/insomnia/sleep-hygiene-tips/

So I officially started my vegan diet a few days ago. One thing I’ve noticed is that I have been sleeping terribly each night since. And it seems to be getting progressively worse. I fall asleep just fine, but I wake up multiple times throughout the night and have trouble falling back asleep. Nothing has changed in my sleep regimen or daily habits, so the new diet appears to be the culprit.

I consulted the almighty (google) and have found some articles linking lack of calcium to night time awakenings, lack of iron to restless leg syndrome, and various other deficiencies common with vegan diets to various other sleeping problems.

Would be very helpful if you could possibly do an article and/or video on the various sleep problems that can result from going vegan as well as the potential solutions.

While most of the studies I looked at cited how a vegan diet would enhance your sleep, I did find one reliable article that may provide some help to you:https://www.pcrm.org/nbBlog/eat-your-way-to-a-good-nights-sleep In this article Dr. Bernard states “…high-protein plant-based foods, like tofu, beans, and lentils, are very nutritious. But if you’re having trouble sleeping, try eating these foods earlier in the day.” You might try this and also check out: https://sleepfoundation.org/sleep-topics/diet-exercise-and-sleep Do try these sleep enhancing tips, experimenting and perservering, so you can continue on your better nutrition path while still getting a good nights sleep!

Thanks for the follow up. My sleep regimen is pretty on point. I get a reliable 9 solid hours every night, which is why it was so obvious to me when the four days I began eating vegan just happened to correlate to the worst 4 nights of sleep I’ve had in months. The vegan regimen is definitely the culprit. As such, I’d rather fix the causes than to merely try to cancel them out with new sleep promoting habits/foods.

The articles I could scrounge up suggested that there is a correlation between calcium deficiency and night time restlessness/frequent awakenings. Another between Iron deficiency and restless leg syndrome, and another between both B12 deficiency and Vitamin D deficiency and poor sleep quality. Given that there seem to be no (or in some cases very few) good sources of these vitamins in produce/whole foods, it seems the only options are supplements, which have a pretty pitiful track record of being absorbed/utilized by the body. In fact, on multiple occasions throughout his book, Dr G looks as studies in which vitamin supplements prove to be essentially worthless, implying that all supplements are best avoided.

Given this, I have a hard time believing that the few vitamins not found in vegan foods (B12, D, Calcium, etc) just so happen to be the only vitamins that prove effective in supplement form. So basically what I’m wanting to know is if there are any good, solid vegan sources of Calcium, B12, and Vitamin D. And if not, is there any evidence to suggest that these vitamins in supplement form are, conveniently, effective?

Would kiwi juice work as well or must it be the actual complete fruit ? I ask because I suffer chrocic insomnia and would like to try this and drinking it down quick would be less unpleasant than having to chew through it slowly….